If you followed my last blog posts on using inexpensive lenses like the Carl Zeiss Jena 35 on my A99V you might have been wondering on how to make it fit. The way you pull this off is with a M42 to A-mount adapter. The adapters is fairly inexpensive, ranging from a flat piece of thin piece of metal with a Sony/Minolta A-mount bayonet fitting and a threaded opening for a M42 lens to .. yes the same with confirmation chip glued to them.
The benefit of using the slightly more expensive chipped versions is that the confirmation chip communicates with the camera, telling it that there is a real Sony lens attached. The camera then reads the information from the chip, and applies this knowledge when it determine how to react. The direct effect is that camera will let you use Aperture Priority automatic exposure, so you can select the aperture and the camera will select an appropriate shutter speed. The draw back is that you cannot just use any chipped adapter with any particular lens. The chips information on focal length has to correspond with the lens focal length and f/stop. That’s why I usually end up using a cheap non-chipped adapter, where I can use any M42 lens.
I got 5 different adapters, and each just slightly different in thickness. The cheaper versions has no chip but to be honest it is not the chipped I prefer. You might also be able to see that one of my adapters was a few thousands of an inch to thick. Causing the lens to move too far away from the focal plane, with the loss of infinity focus as an result. The problem got solved by sanding the adapter until it brought the lens close enough to the sensor to focus at infinity. My Chipped Lenses tells the camera that a 50mm f/1.7 lens is attached to it, only problem that its rarely the case.
The adapter attaches neatly to the camera, and is almost invisible once the lens is attached.
Your are about to step into a world of inexpensive, high quality M42 optics. Lenses for this mount has been produced for more than 70 years. There is communities on Facebook that offers clean and restoration of lenses if needed. All it takes is that you are willing to forget modern convenience, become a better photographer by mastering your camera in total manual mode and forcing yourself to think carefully about each frame.
Word of warning
Be very careful when selecting a lens, even though T mount lenses also is 42mm, is not the same, forcing it can result in damage to either the lens or the adapter.
Some lenses has a aperture pin which comes dangerously close to the mirror or connector pins in the A-Mount. On any account this pen has to be pushed down since the aperture control won’t work unless the aperture pin is pressed. For me the solution has to super glue this pin.